Branches of the persistent primitive trigeminal artery--an autopsy case.

An adult autopsy case of the persistent primitive trigeminal artery (PTA) is reported. At the origin of the PTA in the cavernous portion of the internal carotid artery, the PTA branched into the meningohypophyseal trunk and the artery of the inferior cavernous sinus. This might indicate that these arteries were formed at the same embryonic stage. At the cisternal portion of the PTA in the posterior fossa, it also branched into the trigeminal nerve root and pons on the way to the basilar artery. The PTA might have functions for the normal structures even in the case of adults. The PTA passed through the dural foramen, which was located medial to Meckel's cave, and connected with the basilar artery. The diameter of the PTA decreased markedly at the foramen. The dural foramen might be the site of regression of the PTA during the embryonic stage.